Recently circRNAs have been found in exosomes and characterized as biomarkers in cancer (Li et al., 2015a). Accordingly, they are considered as a potential tool in the diagnosis and clinical treatment of several cancers and neurodegeneration disorders. Advanced sequencing techniques have identified 150,000 circRNAs in various organisms, including >108,000 from humans (Dong et., 2017), but only a few of them have been functionally characterized. For example, circRNA ciR-7 (also known as CDR1as) is highly conserved and abundant in mammalian brain cells (Piwecka et al., 2017). CDR1as functions as a sponge for miR-7 and has been implicated in sporadic Alzheimers disease (Zhao and Shen, 2017), lending strong support to the notion that circRNAs could be involved in neurodegenerative disorders. However, the role of circRNAs in neuronal differentiation is not known. circRNAs may regulate neuronal cell differentiation by modulating the function of potential biding partners such as transcription factors, microRNAs, or RNA binding proteins (RBPs). With guidance from LNS staff (Zhang, Cheng), we have established neuronal cell lines differentiation protocols with retinoic acid (RA) and neural growth factors (NFG) using PC12 cell line. In follow-up studies, we are planning to generate differentiated cells (LGG) for circRNA-sequencing (circRNA-seq). Similarly, we will use differentiated primary neurons for circRNA-seq. This analysis will reveal differentially expressed circRNAs upon neuronal cell differentiation. We will validate differentially expressed circRNAs by RT-qPCR analysis and will study their impact upon neuronal differentiation. The circRNAs identified and validated in will be studied in aging using SLAM brain tissues (TGB).